<SEC-DOCUMENT>0001197817-11-000004.txt : 20110307
<SEC-HEADER>0001197817-11-000004.hdr.sgml : 20110307
<ACCEPTANCE-DATETIME>20110307115630
ACCESSION NUMBER:		0001197817-11-000004
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110304
FILED AS OF DATE:		20110307
DATE AS OF CHANGE:		20110307

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GSI GROUP INC
		CENTRAL INDEX KEY:			0001076930
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS ELECTRICAL MACHINERY, EQUIPMENT & SUPPLIES [3690]
		IRS NUMBER:				980110412
		STATE OF INCORPORATION:			A3
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		125 MIDDLESEX TURNPIKE
		STREET 2:		.
		CITY:			BEDFORD
		STATE:			MA
		ZIP:			01730
		BUSINESS PHONE:		781-266-5700

	MAIL ADDRESS:	
		STREET 1:		125 MIDDLESEX TURNPIKE
		STREET 2:		.
		CITY:			BEDFORD
		STATE:			MA
		ZIP:			01730

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GSI LUMONICS INC
		DATE OF NAME CHANGE:	19990401

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GSI LUMONICS
		DATE OF NAME CHANGE:	19990331

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	LUMONICS INC
		DATE OF NAME CHANGE:	19990115

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BELLANTUONI ANTHONY J
		CENTRAL INDEX KEY:			0001197817

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35083
		FILM NUMBER:		11667314

	MAIL ADDRESS:	
		STREET 1:		GSI GROUP CORPORATION
		STREET 2:		125 MIDDLESEX TURNPIKE
		CITY:			BEDFORD
		STATE:			MA
		ZIP:			01730
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-03-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001076930</issuerCik>
        <issuerName>GSI GROUP INC</issuerName>
        <issuerTradingSymbol>GSIG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001197817</rptOwnerCik>
            <rptOwnerName>BELLANTUONI ANTHONY J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GSI GROUP CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>125 MIDDLESEX TURNPIKE</rptOwnerStreet2>
            <rptOwnerCity>BEDFORD</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01730</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Corporate Resources</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-03-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>438</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19967</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On July 23, 2010 (the &quot;Effective Date&quot;), the Final Fourth Modified Joint Chapter 11 Plan of Reorganization for MES International Inc. (&quot;MES&quot;), GSI Group Inc. (the &quot;Company&quot;) and GSI Group Corporation (&quot;GSI&quot; and, collectively with MES and the Company, the &quot;Debtors&quot;), as confirmed by the United States Bankruptcy Court for the District of Delaware on May 27, 2010 (the &quot;Plan&quot;), became effective and the Debtors emerged from Chapter 11 protection.   In connection with the Plan, (i) all common shares and vested share rights of the Company that were outstanding prior to the Effective Date (collectively, the &quot;Old Common Shares&quot;), were issued to holders of such Old Common Shares under the Final Plan on a one-for-one basis, subject to a 6.165% escrow as contemplated in the Plan.   On March 4, 2011, the New Common Shares subject to the 6.165% escrow were released to the Reporting Person.</footnote>
        <footnote id="F2">Reflects the Company's 1 for 3 reverse stock split effectuated on December 29, 2010.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Anthony J. Bellantuoni</signatureName>
        <signatureDate>2011-03-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
